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The menstrual cycle is an amazing coordination of hormones and signals working together to produce changes throughout the body. Your reproductive system should make you feel incredibly proud to be a woman--it is a beautiful and wonderful system. My hope is that after reading this you'll know more than you ever thought possible about your menstrual cycle. If nothing else, I hope you use this to become more aware of your body and yourself. It doesn't matter if you never decide to start charting; knowing about their cycles is information every woman should have.In this section, we'll be describing a regular menstrual cycle, so this may not apply to women who have variations in their periods due to medication (including hormonal birth control), medical issues such as PCOS, endometriosis, or annovulation, or otherwise irregular cycles. An average menstrual cycle is anywhere from 24 to 36 days long. Let's start with the first half of your cycle: your follicular phase.

Follicular Phase: Day 1 Until Ovulation

TheFollicularPhase, or first half of your cycle, can vary in length. It covers the time from the first day of your period until ovulation. The first day of your period is always the first day of your cycle. Usually, your follicular phase is anywhere from one to three weeks long.

Let's take a look at what happens in each area in your follicular phase:

OVARIES

During these first few days of your cycle, one of the ovaries starts to prepare about 15-20 follicles to develop, each encasing an egg in the ovary. The immature eggs develop slowly over the course of about two weeks. One egg is chosen to be released from the ovary, and the remaining eggs disintegrate and get reabsorbed by the body. The winning egg finishes maturing, and when it's ready, it bursts through the ovarian wall into the fallopian tube. Tada! Ovulation! After ovulation, the ovarian follicle that released the egg (the corpus luteum) begins to disintegrate as well. As it dissolves, it releases progesterone, which will continue to be released for the next 12-16 days in the second half of your cycle (your Luteal Phase).

UTERUS

While your ovaries are busy preparing eggs and ovulating in the first few of weeks of your cycle, your uterus is simultaneously preparing itself as well. The first few days of your cycle are marked by your period, or the shedding of your endometrium. The average period can be anywhere from 2-7 days long. Once your period is over, your body immediately starts to rebuild the endometrium in case of fertilization.

CERVIX

While the eggs are busy developing in the ovaries and your endometrium is rebuilding, the cervix is also preparing for ovulation as well. In the days leading up to ovulation, it starts producing fertile cervical fluid from cervical crypts, small ducts in the cervix. It is this fluid that allows sperm to live longer in the uterus and fallopian tubes. Without this fluid present, sperm can only survive the acidic environment for a few hours at most--certainly not long enough to find and fertilize an egg. Fertile cervical fluid provides safe transport for the sperm to reach the fallopian tubes.

The cervix also undergoes physical changes around ovulation. It widens and withdraws back toward the uterus. It is this change, along with your temperature shift and the presence of fertile cervical fluid, that will help you pinpoint when your ovulation occurs.

The second half of your cycle is called your Luteal Phase.

Luteal Phase: Ovulation to Menstruation

While the Follicular Phase can vary from cycle to cycle in the same woman, the Luteal Phase is usually incredibly consistent. The onset of ovulation in the first half of your cycle can be delayed by stress, malnutrition, or illness, but once the luteal phase starts, it is virtually impossible to stop.This is actually quite handy, though, because the end of the Luteal Phase marks the first day of a new cycle with the arrival of--you guessed it--your period. So, if you know the length of your luteal phase, you will always know the date of your next period.So, let's talk about what happens in your luteal phase. A day or two after ovulation, your cervix closes and becomes low and firm again, and your cervical fluid dries up. Both of these changes are signaled by the release of progesterone from the corpus luteum in the ovary. They will both stay this way until the next time your body prepares to ovulate in the next cycle.Your luteal phase always starts after ovulation has occurred. The length of the luteal phase is usually anywhere from 12-16 days, although it can be as short as ten. Anything shorter than ten days can make it problematic to conceive, because it doesn't give the egg time to properly implant in the endometrium. (Even a ten-day luteal phase can sometimes be problematic.) A too-short luteal phase can also indicate hormonal imbalances or other problems with your cycle.The length of the luteal phase is determined by the amount of progesterone released by the corpus luteum (remember that guy? The follicle that released the egg?). Like we talked about earlier, when the egg enters the fallopian tube, the corpus luteum stays behind and releases progesterone. It is this progesterone that sustains the endometrium in case of implantation and pregnancy.The egg will only live for about 24 hours from the time it is released, although it can live as little as 12. Progesterone quickly prevents the release of multiple eggs after a 24-hour period, so that means that about two days into your luteal phase, you are completely infertile with no chance of pregnancy (until your next ovulation, of course).If fertilization and implantation happens, the corpus luteum continues to release a hormone, but this time it is the more well-known hCG--the hormone that is used to determine if you are pregnant or not. This hormone suspends ovulation and signals the body to sustain the pregnancy.

If conception and implantation doesn't occur, the progesterone will gradually decrease. When no implantation is found, no hCG is produced and your ovaries signal your body to shed the endometrium. You start a new cycle with the beginning of your period.

Why Does This Matter?

Why should you know what happens during your menstrual cycle? Here are just a couple of reasons:

You will know several basic pieces of information vital to understanding your potential fertility: Am I ovulating? Is my luteal phase too short to sustain implantation? Am I getting pregnant and mistaking it for a late period when I miscarry early?

You can know the date of your next cycle without having to worry about it coming during a range of dates (this is especially helpful if your cycles are irregular or unpredictable; even though the first half may vary, remember that the luteal phase is almost always the same length in each individual woman).

If you know when you ovulate, you can know exactly when you can and cannot get pregnant each month.

You can use this information to become more aware of your body and yourself. It doesn't matter if you never decide to start charting; knowing this is information every woman should have.